Sumdum Chief

Mine, Probably inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu; Pb; Zn
Ore minerals chalcopyrite; galena; gold; pyrite; pyrrhotite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SD
Quadrangle map, 1:63,360-scale C-5
Latitude 57.64586
Longitude -133.4697
Nearby scientific data Find additional scientific data near this location
Location and accuracy This site is plotted at the portal of the main the adit of the Sumdum Chief Mine but the underground workings extend for about 4,000 feet to the southwest. The portal is about 1.8 mile south-southeast of the abandoned town of Sumdum at the head of Sanford Cove. The portal is about 0.3 mile south of the center of section 1, T. 49 S., R. 74 E.

Geologic setting

Geologic description

The Sumdum Chief Mine was discovered in 1889 and there was a small test shipment in 1890 (Becker, 1897; Spencer, 1906; Roppel, 1971; Kimble and others, 1984). The deposit consists of two veins, the Bald Eagle and the Sumdum Chief. Originally these was separate properties but were consolidated into a single mine in 1899. Most of the mining took place from 1895 to 1903 when the ore bodies were exhausted and diamond drilling was unsuccessful in finding additional ore. There has been no mining since 1903 although there was some exploration from the main haulage level in 1907 to exploit other claims nearby. A 10-stamp mill was erected in 1895 and the mine was serviced by an aerial tramway and a corduroy road from the community of Sumdum on Sanford Cove to the mill. The veins were mined from a 3,500 haulage drift with an the adit at about 750 feet elevation. Both veins were stoped from this haulage drift to the surface. From 1895 to 1903, the mine produced 24,000 ounces of gold and about the same amount of silver; the average grade of the ore was about 0.39 ounce of gold per ton.
The Bald Eagle vein was intersected by the main haulage level at a depth of about 500 feet where it was about 20 feet wide and contained 0.5 to 1.0 ounce of gold per ton (Spencer, 1906; Buddington, 1925; Kimble and others, 1984). The Sumdum Chief vein was intersected at a depth of about 1,200 feet where it was only a narrow vein; however, on the surface it was 3 feet wide. Both deposits consist of quartz veins and stringers with minor amount of pyrite, pyrrhotite, sphalerite, galena, chalcopyrite, and gold. The best values occurred in pockets and where small transverse veins intersected the main veins. The overall trend of the workings indicate that the veins strike about N80E and dip steeply. The veins generally were parallel to the foliation of the host rocks which were variously described as green slate, black bituminous slate, slate, and graphitic limestone; all are part of the Cretaceous green schist unit of Brew and Grybeck (1984). The deposit at the Sumdum Chief Mine has been dated at 55.1 plus/minus 0.2 million years by Goldfarb and others (1997); like others in the Juneau Gold Belt it is thought to have been formed by fluids generated by Cretaceous metamorphism that were then forced to the site of deposition by the emplacement of the Coast Range Batholith.
When Kimble and others (1984) did their mineral survey of the area, almost all of the old workings were caved and the area was heavily timbered. However, at an elevation of about 1,600 feet, they discovered the top of a stope on what is probably the Sumdum Chief vein. A 1-foot chip sample across the vein contained 0.88 ounce of silver per ton, 0.70 ounce of gold per ton, 940 parts per million (ppm) copper, 1.900 ppm lead, and 3,100 ppm zinc.
Geologic map unit (-133.471414871198, 57.6455197850132)
Mineral deposit model Low-sulfide, gold-quartz vein (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization The deposit at the Sumdum Chief Mine has been dated at 55.1 plus/minus 0.2 million years by Goldfarb and others (1997).

Production and reserves

Workings or exploration The Sumdum Chief Mine was discovered in 1889 and there was a small test shipment in 1890 (Becker, 1897; Spencer, 1906; Roppel, 1991; Kimble and others, 1994). The deposit consists of two veins, the Bald Eagle and the Sumdum Chief. Originally these was separate properties but they were consolidated into a single mine in 1899. Most of the mining took place from 1895 to 1903 when the ore bodies were exhausted and diamond drilling was unsuccessful in finding additional ore. There has been no mining since 1903 although there was some exploration from the main haulage level in 1907 to exploit other claims nearby. A 10-stamp mill was erected in 1895 and the mine was serviced by an aerial tramway and a corduroy road from the community of Sumdum on Sanford Cove to the mill. The veins were mined from a 3,500 haulage drift with an the adit at about 750 feet in elevation. Both veins were stoped from this haulage drift to the surface.
Indication of production Yes; medium
Production notes From 1895 to 1903, the mine produced 24,000 ounces of gold and about the same amount of silver; the average grade of the ore was about 0.39 ounce of gold per ton.

Additional comments

The Sumdum Chief Mine is on patented ground but the surrounding area is part of the Chuck River Wilderness Area which is closed to mineral exploration and mining.

References

MRDS Number A013337

References

Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Redman, Earl, 1988, History of the mines and miners in the Juneau gold belt: Juneau, Alaska, privately printed, 294 p.
Roppel, Pat, 1971, Sumdum: Alaska Journal, v. 1., no. 3, p. 47-50.
Reporters Donald Grybeck (U.S. Geological Survey)
Last report date 10/8/2004